Trade Accounts Receivable and Allowance for Doubtful Accounts - Additional Information (Detail) $ in Thousands	3 Months Ended	4 Months Ended	12 Months Ended
	Sep. 30, 2017 USD ($)	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) Installment
Concentration Risk [Line Items]
Revenue recognized from upfront license fee	$ 3,500
Payments received in number of equal installments | Installment			2
Upfront license fee remained in accounts receivable			$ 1,750
Subsequent Event [member]
Concentration Risk [Line Items]
Payment received as license fees		$ 1,750
Accounts Receivable [Member] | Minimum [Member] | Credit Concentration Risk [Member]
Concentration Risk [Line Items]
Percentage of trade accounts receivable of major customers			10.00%